This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Miller, M. L.
Right arrow Articles by Miller, D. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Miller, M. L.
Right arrow Articles by Miller, D. L.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, September 2008, p. 5795-5802, Vol. 28, No. 18
0270-7306/08/$08.00+0     doi:10.1128/MCB.00356-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Non-DNA-Templated Addition of Nucleotides to the 3' End of RNAs by the Mitochondrial RNA Polymerase of Physarum polycephalum{triangledown}

Mara L. Miller{dagger} and Dennis L. Miller*

Department of Molecular and Cell Biology, The University of Texas at Dallas, Richardson, Texas 75083-0688

Received 2 March 2008/ Returned for modification 9 April 2008/ Accepted 10 June 2008

Mitochondrial gene expression is necessary for proper mitochondrial biogenesis. Genes on the mitochondrial DNA are transcribed by a dedicated mitochondrial RNA polymerase (mtRNAP) that is encoded in the nucleus and imported into mitochondria. In the myxomycete Physarum polycephalum, nucleotides that are not specified by the mitochondrial DNA templates are inserted into some RNAs, a process called RNA editing. This is an essential step in the expression of these RNAs, as the insertion of the nontemplated nucleotides creates open reading frames for the production of proteins from mRNAs or produces required secondary structure in rRNAs and tRNAs. The nontemplated nucleotide is added to the 3' end of the RNA as the RNA is being synthesized during mitochondrial transcription. Because RNA editing is cotranscriptional, the mtRNAP is implicated in RNA editing as well as transcription. We have cloned the cDNA for the mtRNAP of Physarum and have expressed the mtRNAP in Escherichia coli. We have used in vitro transcription assays based on the Physarum mtRNAP to identify a novel activity associated with the mtRNAP in which non-DNA-templated nucleotides are added to the 3' end of RNAs. Any of the four ribonucleoside triphosphates (rNTPs) can act as precursors for this process, and this novel activity is observed when only one rNTP is supplied, a condition under which transcription does not occur. The implications of this activity for the mechanism of RNA editing are discussed.

* Corresponding author. Mailing address: Department of Molecular and Cell Biology, The University of Texas at Dallas, Box 830688, Richardson, TX 75083-0688. Phone: (972) 883-2539. Fax: (972) 883-2409. E-mail: dmiller{at}utdallas.edu

{triangledown} Published ahead of print on 23 June 2008.

{dagger} Present address: Department of Biochemistry and Molecular Biology, 1870 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1870.

Molecular and Cellular Biology, September 2008, p. 5795-5802, Vol. 28, No. 18
0270-7306/08/$08.00+0     doi:10.1128/MCB.00356-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.





Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»